1. Field of the Invention
This invention relates to an optical module having a CAN-type package.
2. Related Prior Art
It is known that an optical module having a CAN-type package has two types. One type is for a light-transmitting module that provides a semiconductor laser mounted on a heat sink. Anode and cathode electrodes of the semiconductor laser are connected to respective lead terminals with bonding wires. Another type is for a light-receiving module that provides a photodiode therein. Anode and cathode of the photodiode are connected to respective lead terminals with bonding wires.
These CAN-type packages used in such light-transmitting module and the light-receiving module have three or four lead terminals for extracting and providing an electrical signal to and from optical semiconductor devices, and supply electrical power to devices.
In the CAN-type package, the lead terminal is provided in the stem. The stem has a disk-shape. In order to install a thermoelectric device such as a Peltier device, further to the optical semiconductor device, into the CAN-type package, additional lead terminals must be provided for the thermoelectric device. The devices within the module, as explained above, are connected to the corresponding lead terminal with bonding wires. The arrangement of the lead terminal is restricted to the position where the wire bonding from the device to the lead terminal is possible. However, in the CAN-type package, especially in the case that the device is mounted on the sub-mount that is disposed on the stem, the lead terminal behind the sub-mount can not be connected to the device mounted in front of the sub-mount.
Therefore, an object of the present invention is to provide an optical module in which the restriction relating to the arrangement of the lead terminal is cleared.